Research published earlier this year showing that avian influenza had been found in pigs in 2001 and 2003 went unnoticed outside China because the results appeared in Chinese language journals, according to a news item in the journal Nature.

The findings appeared in January in the Chinese Journal of Preventive Veterinary Medicine, and in May in the Chinese Journal of Veterinary Science. But neither the World Health Organisation, nor the UN Food and Agriculture Organisation, were aware of their publication until one of the authors presented them at the International Symposium on the Prevention and Control of SARS and Avian Influenza in Beijing on 20 August.

Researchers are concerned that H5N1, the virus responsible for the current avian influenza epidemics in Asia, could combine with a human flu virus, such as H3N2, and give rise to a new virus that would be very dangerous to humans. Pigs could provide a place for this to happen. The abstract to one of the Chinese papers warns that "urgent attention should be paid to the pandemic preparedness of these two subtypes of influenza".